On Sun, Oct 8, 2017 at 6:54 PM, Dave Taht <dave.t...@gmail.com> wrote:
> I have been hacking away at netem for a while now in the hope that > eventually - with a great deal more hacking - it could be used to more > accurately emulate shared media like wifi and lte. > > (Some people try to describe these as simplex (which is not true > because you can have multiple destinations), and they certainly are > not duplex, so I tend to say non-duplex and still hope some better > word emerges) > > So... one sticking point for me has been wanting to emulate the fact > that on shared media, that you cannot transmit and receive at the same > time; that these are "coupled" events, and what I'd like to be able to > express might be something like: > > tc qdisc add dev eth0 root netem rate 100mbit coupled some_identifier > ... some tc mirred magic for ifb here ... > tc qdisc add dev ifb0 root netem rate 10mbit coupled the_same_identifier > > "some_identifier" would be a mutex of some sort, and I confess to > not having much grip on the kernel outside of the net/sched directory. > > What facility would be best to try and leverage? It would be created > (globally) on first use, ref-counted (thus destroyed when it goes to > zero), atomically updated... posix shared memory seems too heavyweight > to use.... > > -- > > Dave Täht > CEO, TekLibre, LLC > http://www.teklibre.com > Tel: 1-669-226-2619 > _______________________________________________ > Bloat mailing list > Bloat@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/bloat Since qdisc only see output packets, maybe a overlay device (like a tunnel or vlan), would be closer to what you want.
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